Sourcemap is a free, open source, community-driven project that aims to show users where all the bits and pieces of the products they buy come from. Sourcemaps aren't just for gadgets, either. Users can collaborate to pin down sourcing for products ranging from iPhones to their favourite cereal. The downside is that since the project is still relatively new, there aren't very many sourcemaps available yet.For items that have been sourced, though, the service is pretty interesting. Not only does it literally map the individual materials, but it also gives an estimated carbon footprint for each of them, given the distance they had to travel before becoming part of a greater product.